Alkylation with olefin mixtures



catalyst is prepared at Patented May 9, 1944 UNITED STA'I'ES PATENT OFFICE 2,348,631 ALKYLATION wrrn OLEFIN lvux'ruans Richard N. Meinert, Westfield, N. J., asslgnor to Standard Oil Development Company, a corporation of Delaware N Drawing. Application July 16, 1940, Serial N0. 345,862

8 Claims.

. molecule with monoolen'ns and in particular with specific types of mixtures of monoolel'inssuch as, ior example, ethylene and propylene mixtures, to produce the desired final products.

The aforementioned applications disclose the carrying out of such reactions with a novel alkylation catalyst. It has previously been found that markedly increased yields of alkylation products having the desired motor fuel boiling range may be produced when a substantially saturated aqueous solution'of boron trifluoride is employed as the alkylation catalyst. The exact nature or this catalyst'is not known since according to "Modern Inorganic Chemistry," by J. W. Mellor, several compounds are formed when BF: is added to water. One reaction consists in the hydrolysis of part of the BF: to produce boric acid and Hl-'.

The HF liberated reacts with unhydrolyzed Br: to give HBFl. In addition, BBB: is known to form hydrates with water. It is possible that the actual active catalyst may be one of the above compoundsorsome compounds which have not been identified as yet. .It is also possible that the catalyst is a solution of BF: in HBFl. It is to be distinctly understood that the process of the present invention is not limited to any theory of the reaction and that the claims appended hereto are not to be limited in the light of the above described theory. In effecting the process of the present invention, it is only. necessary that the catalyst be composed of water substantially completely saturated with boron trifluoride.

In making up the catalyst for use in. the inventi'on, water maintained at room temperature has bubbled therein boron fluoride until there is no further-change in weight of the solution. The

lution prior to its introduction in the alkylation reaction.

It is an'object oi the present invention to alkylate isoparatiins with inonoolefinic mixtures in the presence of substantially saturated aqueous solutions of boron trifiuoride to produce normally liquid, saturated hydrocarbons suitable for use as motor mels or as blending agents in motor fuels.

it is an object 01' the present invention to produce improved yields of motor fuels substantially completely saturated in character and boiling within the gasoline range without-sacrificing to precipitate, which is probably boric acid, is filtered from the solution and the solution is then ready for use in the alkylation reaction. Where the temperatures substantially below room temperature, for example at 40 F., and where the subsequent carried out .at substantially the same temperature, the precipitate above mentioned does not appear and there is noneed alkylation'reaction is for filtering the catalyst soso is usually maintained'between about 35 any great extent the octane number which may be obtained by alkylatlng fairly narrow oleiflnic cuts as heretotore practiced in connection with saturated aqueous solutions of boron fluoride.

It is a further object of the present invention to alkylate the isoparaflins, as, for example, isobutane and/or, isopentane, with olefinic mixtures containing ethylene, as, for example, olefinic mixtures of ethylene and propylene, in order to produce improved yields of motor fuels boiling within the gasoline boning range and having high octane numbers.

Other objects will be apparent to those skilled in the art upon a further understanding of the following disclosure.

The temperature for carrying out the reaction 15. and about F., althoughtemperatures outside of this range, as, for example, temperatures lying between 35 F. and F., may be desirably employed under certain conditions. The time of reaction may vary between about 5 minutes and about 3 hours depending upon the other reaction conditions maintained. It is ordinarily deslrable to use reaction times or between about 10 and about 60 minutes except in cases where ethylene is present in extremely large amounts with reference to the other olefins present, in which case longer times, say up to minutes, may be desirable.

It is preferred to carry out the reaction in the liquid phase, and wherethe' higher temperatures are employed the use of superatmospheric presmedium containing an excess of the catalyst.

' the process of the Where isobutane or isopentane are employed as the isoparailinic reactants, the molar excess may range from 1 to 10 or even as high as 30 mols per mol of total oleflnic content of the reaction mixture. Equal molar quantities of isoparafiins and total olefinic content are, however, contemplated and appear to be desirable in many instances. However, wherejethylene-propylene mixtures are employed the increase in isoparaflin. to total olefin mol ratio from 1:1 to at least :1 would appreciably increase the yield of total alkylate butwould not seem to efiect any substantial change in octane number of the product.

Any suitable apparatus which has heretofore been employed for polymerization or alkylation processes may be employed for carrying out the process of the present invention. Unreacted reactants as well as higher boiling reaction prod ucts may be separated from the final product based upon the fresh monooleflns and fresh isoparaifins added to the alkylation unit.

As before indicated, any isoparafiin or any saturated hydrocarbon containing at least one tertiary carbon atom per molecule may be employed either alone or in admixture with one or more of its homologues as one portion of the reactants inthe present invention. It is particularly desirable from a commercial standpoint to employ isobutane and/or isopentane as the paraflinic component of the chargingstock. It is understood, however, that the isohexanes and heptanes may in certain instances be desirable feed stocks in carrying out the present invention.

As the olefinic reactants, it is essential in order to take advantage of the present invention to employ mixtures of olefinic reactants. At least one of these olefins should be ethylene. Thus present invention contemplates the use of such binary olefinic mixtures as ethylene-propylene, ethylene-normal butylenes, ethylene-isobutylene, and the like. It is not necessary that the olefinic component of the feed stock be exclusively composed of two olefins. In other words, it is within the purview of the present invention to employ olefinic mixtures which predominate in two olefinic components, one oi which is ethylene, but which may also contain small amounts of other oleflns. Such a mixture could be produced, for example, by cracking stabilizer gas; This is a very desirable source of C2 and Ca The molar ratio of ethylene with respect to the other olefin present in the olefinic mixture may vary considerably. Thus, for example, the ratio of ethylene to propylene or of ethylene to butylenes may vary between about 3: 1 and about 1:2. It is to be distinctly understood, however,

a that in those instances in which the oleflnic component of the feed predominates in ethylene that the other olefin present therein is present in such amounts that it is not to be considered that the second olefin serves only as a promoter for efiecting the alkylation of ethylene. The amounts of the second olefin such as, for example, propylene, are actually sumciently large to account for material yields of propylene alkylate in the product. The preferred ethylene to other olefin ratio lies within the range of between about 2:1 and about 0.75:1.

The process can .be carried out either as a batch or continuous type of operation. It is preferred, however, to carry the same out continuously from an economic standpoint. It has been found in the present process as in previous alkyling the scope of the appended ation processes that the more intimate the contact between the feed stock and the catalyst, the better the yield of saturated product obtained. In the case of batch operations, mechanical stirrers or shakers are adequate. In continuous operations, turbo mixers, jets of restricted internal diameter, porous thimbles and the like provide ample agitation of the reaction mass. In a'continuous process, boron fluoride may be admixed in small amounts with the feed stock in order to maintain the concentrated boron fluoride-water mixture substantially completely saturated throughout the life of the catalyst, or the boron fluoride may be added in small amounts directly to the catalyst solution to accomplish the same ends. As previously stated, itis advisable in some instances, in order to secure excellent yields and rapid reaction rates, to carry the alkylation under superatmospheric pressures suiiicient to maintain the hydrocarbon reactants in the liquid phase. In addition, this procedure" is advantageous in that upon introducing small amounts of BF: into the reaction, substantially larger amounts of BF: are retained in the liquid reaction mixture. In other words, a supersaturated solution of BF: in water is obtained due to the increased pressure within the reactor.

As the following examples will show, it has been found to be a distinct advantage to be able to alkylate mixtures of ethylene and propylene directly rather than to alkylate ethylene in one unit and propylene in another and then to combine the alkylates from the two products. One advantage lies in the fact that it becomes unnecessary when practicing the present invention to attempt to effectively separate ethylene irom propylene in a C2-C7: traction of a cracked'stabilizer overhead. This work results in a marked reduction in the cost 01' operating such an alkylation unit. The examples are intended to be illustrative of the inveniton disclosed herein and are not to be considered as in any way limitclaims.

Example 1 A mixture of isobutane and saturated aqueous solution of boron fluoride were introduced into an autoclave maintained under a pressure of between about 50 and about pounds per square inch and at a temperature of about 70 F. A commercial mixture of ethylene and Propylene in equal molar ratio was slowly added over a period of about 40 minutes with vigorous agitation of the reaction mixture. The amount of ethylenepropylene added was such that the final mol ratio was about 5 mols oi isobutane per mole! ethylene-propylene. An additional 20 minutes was allowed zior completion of the reaction. The yield of product boiling above isobutane was about 205% by weightbased on the total ethylenepropylene added. The product had substantially hydrocarbon to catalyst volumetric ratio was maintained at about 2: 1.

Example 2 In another experiment conducted under identical reaction conditionaand employing the same teed stocks, catalyst, etc., except that the total isobutane to total olefin molar ratio was maintained at about 2: 1 instead or :1, the yield based upon the total olefin added amounted to about 209%, or which the first traction boiling between 5'7-165 F. constituted 41.4% of the product and to using a mixed olefin feed is possibly one octane number lower than the corresponding blended cut from Examples 4 and 5 whichv have employed single olefins in the alkylation' process.

While this does not appear at first hand to be In every case the corresponding cut with respect the second traction, 165-265 F., constituted 39.6% 5 any distinctadvantage over the prior art, the of the product. The first fraction had an outstanding advance lies in' the fact that the A. .S. T. M. octane number of about 91.6; the quantities of product produced are surprisingly section fraction about 84.7. larger with respect to the combined olefinic feed Example 3 l stock in contrast to the separate alkylation of each or the olefins followed by a blending oi the In this experiment the conditions or the former corresponding cuts. This is clearly brought out runs as outlined in Examples 1 and 2 were duin'the following table:

olefin Product! 57-165 F. out let-265 F.cut 285-400 F. cut Type of alkylation reactant, in

' Wands pmmd' Pounds 0. N. Pounds 0. N. Pounds 0.- N.

1 Ethylene 40 p 90 55 92.5 27 a2 s 78 2 Prop lene 60 123 ll 87 81 70 31 '84 a Blen oilwithz 100 213 ea 92 we so a9 a2 4 Ethylene-propylene. 100 210 87 91.7 83 85 40 81 plicated, both as to reaction conditions and cata- In the table, 0. N. indicates octane number lystand reactants, except that the ethylene to by the A. S. T. M. method. The type of alkylapropylene molar ratio in the olefinic portion of tion is designated as ethylene, indicating that the the feed was maintained at about 1.4:1 while the olefinic component was solely ethylene, or propyltotal isobutane to total olefin molar ratio was one for an olefin solely propylene. No.3 is a maintained as in Example 2. The yield amounted blend of the two alkylates separately prepared in to about 205% by weight based on the total ole- No. 1 and No. 2, and No. 4 is an 'alkylate prepared fins employed, or which 48.5% constituted the from the mixed ethylene-propylene olefinic teed. 57-165 F. cut and 40.8% the 165-265 Rout. The It is at once apparent from the above table first out had an octane number by the S. '1. M. that there is actually an advantage in alkylating method of 91.7, while the second out had an the ethylene-propylene mixture (No. 4) to pro- A. S. T. M. octane number of about 84. duce 87 weight based on total olefin of a 57-165 F. out having an octane number of 91.7 ple 4 as compared to a 66 weight alkylation product a of the same cut having an octane number of 92 Under cqndmons mmmiable to Example obtained when each olefin is separately alkylated made empmymg ethylene as the 46 with isobutane and the cuts blended. While of the feed.swck' There was there is a slight dropping oil of the octane numtamed. a product substantially completely satuher for the traction when employing a mixed rated inphamcter m a yield of about 225 weight olefin teed stock for the alkylation, nevertheless per based the ethylene, of this pmduct there isan increase or 21 weight in the product 61% boiled between 57 and 165 F. and 30% beobtained which roughly, varies in octane tween and octane number of her from the separate alkylations oi the olefins the first fraction by the A. S. T. M. method was by about of an octane number 92.5, whereas the octane number oi the second As prevmusly pointed ut, the products obfraction was tained by this method are highly useful-tor mo- Example 5 50 tor fuels per se, particularly in the field 0! aviation gasoline, or the products may be used as Under conditions comparable to those set forth blending agents for convenient gagoflnebase n Example 1. except that the ethyle -P l stocks for the manufacture of gasoline of the deolefinic feed stock w s replaced, y Propylene sired characteristics for general automotive puralone, a product was obtained in about 205 weight poses Yieldfi' the Pmpyleneof thisvQ-w When used in the specification and claims, the Weight boiled between 57 and and 66 expression substantially saturated aqueous soluboiled between and 265 F. The tion f boron trifluoride" or ex re io first and second fractions v11941 T -l equivalent thereto is intended to cover a catalyst numbers about containing substantially only water, boron tri- Up n blen ing thefirst fmctlon the Product "fluoride and any product of the reaction of these pr d in E ple 4 with the first fraction f two'materials under thereacti'on conditions suitt e p o uct, p o in Example t octane able for the alkylation reaction. As previously number'by the M- mefihodwasmund t0 pointed out, the, exact composition of the catalyst be 9 Li e i by blending the se f n as is unknown. Since it has been fairly well ascer- Of each 01 the two p e gexamp s the octane tained thatsome reaction does take place between numbelf f the blend y the methc'd boron trifiuoride and water and that these prod- W f n to be It Will be noted that in 0011- ucts of this reaction may in and of themselves ct to i Octane n m r, the octane number constitute catalysts for the alkylation reaction, of the same fraction produced accordin 3 it is intended that the claims so cover these commp 1 and ZWfiS almost 5 8 as that Obe pounds, whatever their chemical nature may be. tained according to Exampl s 4 and This 15 Having described the invention in full, what is also true ,with respect to the second fractions desired t be secured and claimed by Letters when compared onthe basis of octane number. p t t 7 1. A process for producing improved yields of motor fuels boiling within the gasoline range and having improved octane number which comprises alkylating at least one isoparaflin with a normally gaseous olefinic mixture of ethylene and at least one other monoolefin wherein the molar ratio of ethylene to other m'onoolefins is between about 3:1 and about 1:2, in the presence of a substantially saturated'aqueous solution of boron trifluoride, under alkylation reaction conditions.

2. A process for producing improved yields of motor fuels boiling within'the gasoline'range and having improved octane number, which comprises alkylating isobutane with an olefinic mixture of ethylene and propylene, the olefins being in the molar ratio of between about 3: 1 and about 1:2, at a temperature between about 35 F. and about 80 F. in the presence of a substantially saturated aqueous boron trifluoride solution, and intensively agitating the reaction mixture during the reaction.

3. A process as in claim 2 wherein isopentane is substituted for the isobutane'.

4. A process as in claim2 wherein the reaction is carried out continuously.

5. A process for producing improved yields of motor fuels boiling within the gasoline range and having improved octane number which comprises alkylating isobutane with an ethylene-propylene mixture, the ethylene and propylene being present in substantially equal molar amounts, at a temperature of about F. for about one hour, with intensive agitation, in the presence of a substantially saturated aqueous solution of boron trifluoride and under suflicient superatmospheric pressure to maintain a substantially liquid phase reaction under the conditions obtaining.

6. A process as in claim 5 wherein the isobutane is present in substantial molar excess over the total oleflnic content present in the reactor at any one time and wherein the total hydrocarbon to total catalyst volume ratio in the reactor is maintained at at least about 2 1.

7. A process for producing improved yields of motor fuels boiling within the gasoline range and having improved octane number which comprises alkylating isoparaflin with a normally gaseous monooleflnic mixture of ethylene and at least one 04 monoolefin, wherein the ethylene to C4 monoolefin molar ratio is between about 3:1 and about 1:2, at a temperature between about 35 F. and about F. in the presence of a substantially saturated aqueous boron trifluoride solution while maintaining alkylation reaction conditions.

8. A process as in claim '7 wherein the ethylene to C4 monoolefin molar ratio is between about 3:1

and about 1:2, wherein the isoparaflin is isobutane and wherein the reaction is carried out continuously,-the catalyst layer separated from the hydrocarbon layer and returned to the reaction zone. A

- RICHARD N. MEINER'I. 

